Perenniality enhances soil biological function in U.S. farming systems

Abstract

Current U.S. farming systems, dominated by annual high-input monocultures, have contributed to environmental problems, including soil degradation. Increasing crop diversity, particularly through the inclusion of perennial species, and adopting circular farming practices such as integrating grazing and legumes, have been proposed to improve ecosystem services and resilience. This study aimed to identify and characterize local dominant systems (LDS) and diverse perennial circular systems (DPCS) across three U.S. regions; analyze the relationships among diversity, perenniality, and circularity (legume and/or grazing integration) across farms; and assess their associations with soil health indicators. A total of 52 paired farms were characterized, classified as either LDS or DPCS. Farm data were collected through three online surveys capturing information on land use, main crops, and livestock production. Soil samples were taken from similar soils within each pair and analyzed using soil health indicators. The five soil health indicators used as response variables were soil organic matter (SOM), cation exchange capacity (CEC), soil respiration, microbially active carbon (MAC), and soil health score (SHS), as determined by the Haney test. Circularity correlated positively with both perenniality (P < 0.01) and diversity (P < 0.01), but perenniality emerged as the only variable significantly associated with improved soil biological activity, as revealed by increased microbial respiration (P < 0.01), MAC (P < 0.01), and SHS (P = 0.06). These findings highlight the value of integrating perennials to enhance soil function in agricultural systems traditionally dominated by annual cropping.